can we sum this up to microstutter? especially the nature of low end crossfire systems, run a benchmark and tell me if you minimums are worse with 2 cards then it is with one, crossfire is crap especially on the low/mid end
it doesnt sound like microstutter, microstutter is "MICRO" meaning you barely notice it and happens within a millisecond and happens constantly. He is experiencing playability followed by a crash in FPS for a couple seconds.
Do other games have the same issue? i would suggest downloading driversweeper and running it, following all the instructions to remove every trace of your display driver, then only re-installing the latest AMD driver. Also if you got a blue screen and now your save games arent working, this sounds like you might have corruption of the game and/or hard drive. Run memtest 86+ and run the hard drive manufacturers hard drive diagnostic tool. If that comes back all clear, reinstall the game.